Как сделать, чтобы эллипс растягивался, а потом сворачивался в WPF?

Если еще актуально то можно так попробывать

<Grid>
        <Label Width="100" Height="50" Background="Tomato" BorderThickness="3" BorderBrush="ForestGreen">
            <Label.Style>
                <Style TargetType="Label">
                    <Setter Property="Template">
                        <Setter.Value>
                            <ControlTemplate>
                                <Border CornerRadius="30" BorderBrush="Transparent" BorderThickness="0" Background="Tomato"></Border>
                            </ControlTemplate>
                        </Setter.Value>
                    </Setter>
                </Style>
            </Label.Style>
            <Label.RenderTransform>
                <TranslateTransform x:Name="LabelTransform" />
            </Label.RenderTransform>
            <Label.Triggers>
                <EventTrigger RoutedEvent="MouseLeftButtonDown">
                    <EventTrigger.Actions>
                        <BeginStoryboard>
                            <Storyboard>
                                <DoubleAnimationUsingKeyFrames Duration="0:0:1"  Storyboard.TargetProperty="Width">
                                    <LinearDoubleKeyFrame KeyTime="0%" Value="100" />
                                    <LinearDoubleKeyFrame KeyTime="10%" Value="110" />
                                    <LinearDoubleKeyFrame KeyTime="20%" Value="120" />
                                    <LinearDoubleKeyFrame KeyTime="30%" Value="130" />
                                    <LinearDoubleKeyFrame KeyTime="40%" Value="140" />
                                    <LinearDoubleKeyFrame KeyTime="50%" Value="150" />
                                    <LinearDoubleKeyFrame KeyTime="60%" Value="140" />
                                    <LinearDoubleKeyFrame KeyTime="70%" Value="130" />
                                    <LinearDoubleKeyFrame KeyTime="80%" Value="120" />
                                    <LinearDoubleKeyFrame KeyTime="90%" Value="110" />
                                    <LinearDoubleKeyFrame KeyTime="100%" Value="100" />
                                </DoubleAnimationUsingKeyFrames>
                                <DoubleAnimation Duration="0:0:1" To="100" 
                                                 Storyboard.TargetName="LabelTransform" 
                                                 Storyboard.TargetProperty="X">
                                </DoubleAnimation>
                            </Storyboard>
                        </BeginStoryboard>
                    </EventTrigger.Actions>
                </EventTrigger>
            </Label.Triggers>
        </Label>
    </Grid>

Или вам целиком контрол надо такова вида